Last updated on Thursday, April 9th, 2020
A week ago the authoritative voices in the U.S. were telling us that face masks weren’t a great idea. The now-famous N95s not only should be saved for the medical professionals and first responders, and they also don’t work well unless they’re properly fitted (all of this, by the way, is still COMPLETELY TRUE). Disposable surgical masks not only should be saved for the medical professionals, first responders, and people who are actively ill, but are also mostly about the wearer not spreading disease rather than about protecting the wearer from getting the disease (all also still true). So the general advice was just to stay away from people rather than wear masks (and staying away from people is, of course, still the best course of action if it’s possible).
Now all of a sudden the CDC says we’re all supposed to wear masks, and I’ve turned nearly every non-working moment toward my new cottage industry of sewing masks for people. (I’ve made 62 so far, mostly over the weekend but also in the couple of hours before work each morning and the couple of hours before bed each night.) I think of the masks I make as a hug that the recipient can throw in the wash!
Of course, being a librarian by trade as well as by temperament, I wanted to choose patterns and fabric based on more than search engine result ranking. What fabrics should I look for? What pattern should I choose? How do you even use one of these effectively?
Sadly, there’s basically no research on homemade face masks for use during an infectious disease outbreak. In fact, there’s one whole study (Chughtai 2013) on how there aren’t studies on this but there should be because what would happen if we ended up in a pandemic and ran out of disposable masks? (Excuse me a minute while I cry into my tea.) Given that, I proceeded to do what all librarians do: look for what does exist from authoritative sources and then triangulate and verify across multiple sources to see if I can figure out a good way forward. Maybe it’s not The way forward, but at least it’s a way that seems best backed by the most authoritative sources I could find.
Basically all the requests for cloth masks that come from hospitals say to use densely woven cotton or cotton/polyester blend fabric, like what quilters use, for the two outer layers of a cloth mask. There are studies on cloth masks made from common household cloth that helps me understand why this is true — for example T-shirt material is only 1/3 as effective as a surgical mask, but tea towels are a bit better, and nothing is as good as actual surgical masks (Rengasamy, Eimer, and Shaffer 2010; MacIntyre et al. 2015; Davies et al. 2013). Basically, fabrics are all so different, even if they’re made of similar materials, that scientists just can’t really predict which ones will absolutely be best (Rengasamy, Eimer, and Shaffer 2010; Shakya et al. 2017). The same fabric might even improve over time after multiple washings (Kim 2017), so definitely launder your masks (recommendations include laundering before sewing so that they won’t shrink afterwards, and then laundering after every use because after you’ve worn it it’s probably come in contact with the virus). Then we come to the triangulation part of the research process, and basically lots of different scientists and medical professionals are quoted in lots of different news outlets and sewing instructions from hospitals saying variations on “the tighter the weave the better, but you also have to be able to breathe through it.” So that’s what I’m going with – tight woven fabric, not knitted t-shirt fabric.
Then there’s a common element in hospital requests for a “non-woven” filter material between the outer layers of the mask. Actual surgical masks are made of non-woven material because they don’t have all those tiny holes where the threads overlap — fewer/smaller holes means better protection — and this has been the case for a long time now (Furuhashi 1978). Again, triangulating from interviews with medical professionals in various news outlets, things like vacuum cleaner bags and HEPA are awesome but can get harder to breathe through, those blue shop towels are great, and paper towels are better than nothing. The CDC recommends a coffee filter.
I don’t have non-woven fabric, so that means I’ll need to chose a pattern to make that allows for paper filters to be inserted.
Choosing the pattern
There are SO many patterns out there. If you’re making masks to donate to a healthcare institution, use whatever pattern they ask for. If you’re making masks for places that don’t specify a pattern, here are the common elements I found as I triangulated everything I could read on the subject.
- It must fully cover the nose and mouth
- It should have two layers of cloth
- It must fit as closely to the face as possible (no gaps by your chin, cheeks, or on either side of your nose)
- If it doesn’t have a built-in non-woven filter material, it should have a pocket so that wearers can insert filters.
- It should be sturdy enough to withstand washing. Lots of washing. People should be washing these masks after every use.
Anything that meets these criteria will be a fine pattern, so if you find one you like, go for it!
I experimented with a bunch of patterns (pleated versions and contoured versions), and for my own work I decided on a pattern that maximized the important coverage and fit requirements while minimizing fabric use. I also experimented making masks with and without a wire over the nose (inserting it is fiddly, and it has to be either removable or washable) and decided that the fit is a whole lot better with the wire. The pattern I chose also seems to work best for people who wear glasses, since it stays away from the eye area better. On the down side, I actually need a pattern to cut around since it’s not just a rectangle, and it takes longer to sew each mask.
If you want to make what I’m making, here are instructions. Feel free to borrow, modify, share, whatever.
My Conclusions as a Librarian, not a Doctor
A lot of the benefit of these masks probably comes from helping us remember not to touch our faces. If made well, used properly, and laundered after each use, they may also help contain any germs that we breath/cough out, and they might filter out some of the germs around us before they get into our bodies. So I’m going to make masks, and I’m going to wear them, but just as the CDC’s guidelines suggest, I’m not going to think of them as magical virus blockers that make it safe for me to go out and do stuff near other people.
Chughtai, Abrar Ahmad, Holly Seale, and Chandini Raina MacIntyre. 2013. “Use of Cloth Masks in the Practice of Infection Control – Evidence and Policy Gaps.” International Journal of Infection Control 9 (3). https://doi.org/10.3396/IJIC.v9i3.020.13.
Davies, Anna, Katy-Anne Thompson, Karthika Giri, George Kafatos, Jimmy Walker, and Allan Bennett. 2013. “Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?” Disaster Medicine and Public Health Preparedness 7 (4): 413–18. https://doi.org/10.1017/dmp.2013.43.
Furuhashi, M. 1978. “A Study on the Microbial Filtration Efficiency of Surgical Face Masks–with Special Reference to the Non-Woven Fabric Mask.” The Bulletin of Tokyo Medical and Dental University 25 (1): 7–15.
Kim, Seung Won. 2017. “Changes of Particle Filtration Efficiency of Cloth Masks by Machine Washing and Cloth Expansion.” Journal of Korean Society of Occupational and Environmental Hygiene 27 (2): 115–22. https://doi.org/10.15269/JKSOEH.2017.27.2.115.
MacIntyre, C. Raina, Holly Seale, Tham Chi Dung, Nguyen Tran Hien, Phan Thi Nga, Abrar Ahmad Chughtai, Bayzidur Rahman, Dominic E. Dwyer, and Quanyi Wang. 2015. “A Cluster Randomised Trial of Cloth Masks Compared with Medical Masks in Healthcare Workers.” BMJ Open 5 (4): e006577. https://doi.org/10.1136/bmjopen-2014-006577.
Rengasamy, Samy, Benjamin Eimer, and Ronald E. Shaffer. 2010. “Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 Nm Size Particles.” The Annals of Occupational Hygiene 54 (7): 789–98. https://doi.org/10.1093/annhyg/meq044.
Shakya, Kabindra M, Alyssa Noyes, Randa Kallin, and Richard E Peltier. 2017. “Evaluating the Efficacy of Cloth Facemasks in Reducing Particulate Matter Exposure.” Journal of Exposure Science & Environmental Epidemiology 27 (3): 352–57. https://doi.org/10.1038/jes.2016.42.